The present invention pertains to crane boom stops and, more particularly, to an improved hinged boom stop arrangement.
Cranes and other load handling equipment with elongated booms pivotally mounted for movement in a vertical plane are frequently provided with some form of boom stop device to provide a positive upper limit of boom travel as well as to control boom recoil which may occur upon the breaking of a lifting cable or during movement of the crane over rough terrain, for example. One class of boom stop devices are the hinged boom stops. These boom stop devices consist, generally, of a compression strut which is pivotally connected at one end to the crane superstructure and a link strut pivotally connected at its opposite ends to the boom and to the compression strut, respectively, with the lengths of the compression and link struts and the locations of the pivotal connections being such that the compression strut contacts the boom when the boom is raised to its maximum working elevation. U.S. Pat. Nos. 2,999,601, Mork, and 3,647,087, Mooney, provide examples of boom stop devices of the hinged type.
On many cranes equipped with hinged boom stop devices, the lengths and mounting points of the compression and link struts are such that the boom stop device must be disconnected when the crane boom is to be lowered from the lower limit of its operating range to a ground engaging position. This is an undesirable arrangement as it is time consuming. Also, the presence of a readily removable connection between the boom stop device and the crane or boom structure makes it possible to inadvertently operate the crane without the boom stop device being in its operative condition, thus defeating the intended safety features of the boom stop device.
It is the primary object of the present invention to provide a hinged boom stop arrangement which permits full lowering of the crane boom without any disconnecting or disassembly of the boom stop or of the connections between the boom stop and the crane and boom structures.
It is also an object of the present invention to provide a boom stop arrangement permitting full lowering of the boom and which automatically assumes an operative position when the boom is elevated to any angle within the working range thereof.
A further object of the present invention is the provision of a boom stop device of the compression and link strut type permitting full lowering of the boom without the use of complex linkage arrangements.
Another object of the present invention is the provision, in a boom stop device having a compression strut and a link strut, of means permitting the full lowering of the crane boom without the need for the disconnection of any portion of the boom stop device, the means being readily adaptable to existing compression and link strut boom stop devices.